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Designing a very, very large airliner…

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Designing a very, very large airliner…

Old 6th Feb 2016, 21:35
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Designing a very, very large airliner…

…yes it may not have much business sense right now but I had this nagging curiosity on how big airplanes can get since the flight of the A380. Yes you can say there’s no limit from a technical standpoint. As long as you have enough materials and power, a plane with a 10 kilometer wingspan carrying a million people can be built, right? But I’m not here to argue that.

It has been stated that the A380 (particularly the planned but undeveloped A380-900) maxes out the 80x80m box agreed upon by airports around the world. How can an airliner become even bigger without rewriting all the rules of airport infrastructure, without inventing extremely advanced technologies and without sacrificing comfort and performance big jetliners have today? The question is: what is the biggest airliner we can build and certify now?

I’ve taken a look at several concepts intended for large transport aircraft from flying wings to “sky-whales” until I found a design with huge potential for VLAs. It’s called the box wing.

Here’s a video of a box wing being tested in flight.

More about box wings here. Also see page 45 further explaining the potential of box wings for very large aircraft.

So here is my design solution:






WINGS

More reasons why I chose a box wing:

1. In a forward-backward swept wing combo with enough vertical separation a box wing will have a huge lifting capability needed for a wingspan-constrained aircraft.
2. It naturally has very good vortex reducing wingtip devices.
3. It has a relatively strong structure compared to a single cantilever wing. This can allow for a thinner, lighter wing structure.
4. Box wings can eliminate the need for a separate horizontal stabilizer.
5. The brackets that close the wingtips can double as a vertical stabilizer and rudder.
6. The wing configuration can allow significantly more yaw, pitch and roll control options.
7. Engines can be mounted on the top wing giving them significant ground clearance to prevent ingestion of FOD. This also allows for space for ever expanding bypass ratios of aircraft engines.

FUSELAGE

Making the most out of the lift the wings are capable of, I found a triple-decker, multi-bubble to be the best design: 3-4-3 upper deck, 3-6-3 main deck and 3-6-3 lower deck giving the cross-section total of 34-abreast compared to total 18-abreast (potential 19-abreast) A380. This easily fits 1,000 in 3-class configuration. The design also eliminates the need for three or more aisles which poses hazards to emergency evacuation process.

FRONT CENTER WING BOX

To make this plane competitive in belly cargo capacity, I have placed the front center wing box through the lower deck cabin. This design makes for a continuous belly cargo hold that can accommodate 94 LD3 containers. There will be two corridors cutting through the wing box that will act as passage between the front and rear cabin. Instead of fuel tanks, the leftover space can be used for galley storage leaving the rest of the cabin for passengers.

PASSENGER/CARGO LIFT

Aside from the two staircases, the three passenger decks will be connected via lift. This is for the purpose of transporting persons with disability between decks as well as beverage trolleys, among many others. The lift will be located aft of the wing box.

ATRIUM & MEZZANINE

Since the curvature of the fuselage nose cone will cause the upper deck’s ceiling to curve downward, the space at the front will be of little use, so I decided to cut the upper deck’s floor short in order to create a mezzanine that overlooks a small atrium on the main deck. This is also where the main staircase is located giving an impression of a grand hall for passengers entering the aircraft. Due to this, the main deck atrium can only have limited overhead bins so this space can be used as a lounge or shop by premium carriers but it can also be used for more seats by LCCs.

I am not a certified engineer whatsoever and I have never formally studied engineering or aeronautics in my life. Compared to professionals, I only have a rudimentary understanding of aircraft design. I have a background though in architecture hence, some proficiency in 3D modeling.

Thank you for taking the time to read my post. I’ll post more detailed renderings soon. Anyway could it work? What do you think?


I have searched far and wide to find a place to share this where there are people with much expertise on the subject. I hope this is the right place to post this. If not, feel free to move this thread. Also I am inspired by keesje with his work with the Turboliner, Greenliner and the Ecoliner among many others.
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Old 7th Feb 2016, 04:30
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Devil Too heavy

I don't think many airports pavement would carry that load. A lot of airports needed strengthening etc for the A380.
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Old 7th Feb 2016, 06:45
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It is a huge undertaking to make an airport usable for the A380. Very expensive and time consuming.The required space for runways, taxiways,clearways and gates is burdensome as is. To go even larger is probably uneconomical. Gate space is at a premium at many airports, larger gates mean less total available.
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Old 7th Feb 2016, 07:21
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Your rudders "J"

They are at the midpoint-ish.

This means that they will not produce yaw. At best they would move the aircraft sideways, though if differential you could get some yaw as a secondary effect I suppose.

Last edited by Tourist; 7th Feb 2016 at 08:11.
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Old 7th Feb 2016, 08:13
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I can only imagine that ground effect must be a pig on landing w.r.t. pitch control in box configuration aircraft.
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Old 7th Feb 2016, 08:18
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Why design an aircraft with 6 engines?
Plenty of room for 4 777 engines.

Less is better for efficiency, reliability (6 times more likely to have an engine failure than a one engined aircraft)
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Old 7th Feb 2016, 08:44
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medviation,
Thanks for an interesting and well presented post.

On the subject of lifting surfaces, particularly of the box design, a distant relative of mine published a number of papers on the subject.
His research produced a number of interesting findings which significantly advanced aviation technology.

You might have heard of him - Lawrence Hargrave.


p.s. He later regularly corresponded with and advised a couple of Americans called Wilbur and Orville.
Thankfully, he lived to see his dream realised - powered and controlled manned flight.
.

Last edited by Stanwell; 7th Feb 2016 at 09:26.
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Old 7th Feb 2016, 09:30
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I think it looks great. A clever way of fitting inside the 80m box while doubling capacity.

As the rudders at 'J' are split, I think they would work just fine for yaw control, using asymmetric drag.

One concern could be the position if the engines behind the front wing. At moderate angles of attack they may encounter disturbed air.

Why don't you send your ideas to the Royal Aeronautical Society? I'm sure they would be interested and have some well-qualified people to give constructive feedback, instead of the nit-picking you may encounter here.
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Old 7th Feb 2016, 09:41
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A fascinating excercise from a drawing point of view! However I can imagine a number of downsides in terms of structural strength, center-of-gravity, air-flow, economics, efficiency, stability, undercarriage, etc.
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Old 7th Feb 2016, 10:36
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Originally Posted by eckhard View Post
As the rudders at 'J' are split, I think they would work just fine for yaw control, using asymmetric drag.
How many aircraft can you think of that use asymmetric drag for yaw control eckhard?

it is just not an efficient way of providing yaw control if you already have vertical surfaces
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Old 7th Feb 2016, 10:44
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Happened in Singapore last year. A number of arrivals left the terminal staff running very thin. There were only enough staff to allow us to board our A380 via one door. Delayed us an extra 30 minutes.
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Old 7th Feb 2016, 11:31
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I'm thinkin' deep stall here... Other than that , it looks great.
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Old 7th Feb 2016, 11:47
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How many aircraft can you think of that use asymmetric drag for yaw control eckhard?
Only one; the B-2. Are there others?

Last edited by eckhard; 7th Feb 2016 at 12:09.
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Old 7th Feb 2016, 12:17
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Originally Posted by eckhard View Post
Only one; the B-2. Are there others?
Not that I can think of, and the B2 does not have them because they are a good idea aerodynamically......
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Old 7th Feb 2016, 12:47
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I can only add to the responses about airports.

It is much, much easier to design and build a very large aircraft such as this one than it is to create the environment in which it can operate at its full potential.

The airport industry has not really caught up with the B747, or any other later aircraft offering similar passenger loads. And the B747 first flew in the 1960's.

Most airports simply create parking stands for the large aircraft, and consider their job done. They might have to upgrade pavement strengths as well.

But the real problems with these aircraft start in the terminal, airdide and landside, where few if any airports are really designed to cope efficiently with the peak flows these aircraft generate. Just as a starter, think how long it takes to deplane a full B747, and then wonder why such nonsense happens. It's not set in the Holy Writ that you can only use 2 doors; but most airport managements and their architects believe that it is, which is why it is now a "fact of life" that no-one dares to challenge. Well, I do. (In BAA that meant a lot of unpleasant meetings, usually with a bunch of grocers talking about "footfall" and how to prolong passengers' misery so that they had more time to buy over-priced tat.)

Intermineable queueing in both directions, crowded discomfort, inability to handle massive disruption for reasons such as fog, are all the consequences of airport owners and managements failing totally to grasp their responsibilities as opposed to maximising their retail spend. The excuse that problems are exacerbated by security does not wash any longer. The industry has had 15 years to catch up with that, or rather the USA has had 15 years, the rest of the world 50 years.

My heart sinks when I see brand new, beautiful, modern terminals (eg LHR T5 and T2) which simply perpetuate the fundamental design flaws of their predecessors, wrapped up to look, but not to be different.

So, my suggestion is to put away the aircraft design, and focus on airport design. Bin all the received wisdoms that architects and layout designers hold so sacred. Start afresh. Use technology imaginatively, rather than as a means of just automating and consolidating existing processes and methods. Unless someone does that, the world's airports will always be the reason we cannot advance.

Last edited by Capot; 7th Feb 2016 at 13:02.
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Old 7th Feb 2016, 13:24
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It looks lovely, BUT

As said above, there would be so many ground handling issues. Checkin, Immigration, baggage, you name it, plus You'd have all manner of PCN issues at that weight.

Maybe it might make a specialised freighter at some adapted airports?

Good luck though
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Old 7th Feb 2016, 13:42
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Wow thanks so much for the many replies!

I don't think many airports pavement would carry that load. A lot of airports needed strengthening etc for the A380.
Good point. But I wasn't too familiar with airport pavement design. I thought if I added more wheels the distribution of weight will be spread out similar to an A380 or 747. Could you share some numbers?


It is a huge undertaking to make an airport usable for the A380. Very expensive and time consuming.The required space for runways, taxiways,clearways and gates is burdensome as is. To go even larger is probably uneconomical. Gate space is at a premium at many airports, larger gates mean less total available.
I think you're missing the point. I'm trying to look at a design that would allow more payload than an A380 without going beyond the runway, taxiway, gate requirements of an A380.


I can only imagine that ground effect must be a pig on landing w.r.t. pitch control in box configuration aircraft.
One concern could be the position if the engines behind the front wing. At moderate angles of attack they may encounter disturbed air.
I'm thinkin' deep stall here...
I guess so, but well never know without simulation and testing.


Why design an aircraft with 6 engines?
Plenty of room for 4 777 engines.

Less is better for efficiency, reliability (6 times more likely to have an engine failure than a one engined aircraft)
I know, except 4 777 engines is not enough. An airplane this size may require 645kN thrust each compared to 514kN of the GE90. This would require a totally new engine technology.
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Old 7th Feb 2016, 14:30
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Manufacturing the complex wing-joint sections would be difficult/expensive...
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Old 7th Feb 2016, 15:51
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Curiosity not criticism - why did you go for that design rather than a Blended wing body with a much larger fuselage volume for the wingspan?


Weight is the limiting factor as much as size though, as mentioned, consideration to paved surfaces and undercarriage. Also wake turbulence for following aircraft... not all aircraft will be anywhere near as big, and something so big will limit approach/departure flow.

Also handling ability, something so big will have a massive turnaround time, not only will boarding/disembarking take forever unless airports utilise more aircraft doors, but also the time spent cleaning/prepping the cabin between pax.


It appears to make more sense for smaller more efficient aircraft, which is why 787/A350 seem to be the future rather than 747/A380
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Old 7th Feb 2016, 16:17
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I've often wondered why the blended wing/lifting body concept hasn't met with much favour.
Vincent Burnelli's lifting body designs (1920s to 1950s) seemed to offer significant advantages in terms of safety, comfort,
economics and operation over conventional designs.

Could somebody enlighten me as to why the 'tin tube' concept continues to dominate?
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